Fabricating integrated circuits or other semiconductor devices involves a sequence of depositing a layer of material, covering the layer with a photoresist, patterning the photoresist to produce a pattern of open areas exposing the material while other areas remain covered by the photoresist. The open areas are etched to produce a pattern in the deposited material. Consistent reproduction of a size, shape and location of the photoresist increases the likelihood the integrated circuits will function as desired.
Insufficient photoresist adhesion limits a resistance of the developed photoresist to peeling or delamination. Peeling and delamination alter the size, shape or location of the photoresist. For example, in some instances, small or narrow photoresist structures peel away from an underlying layer during development thus exposing more of the underlying layer. Peeling is often due to a bonding problem between the photoresist and the underlying layer, or undercutting of the photoresist bonded to the underlying layer along a bottom surface of the photoresist. Undercutting reduces an amount of contact between the photoresist and the underlying layer, thereby further reducing the adhesion therebetween.
Another source of peeling or delamination is the relaxation of the photoresist after development. When internal stresses of the photoresist are relieved, the photoresist retracts resulting in a decreased bonding area between the photoresist and the underlying layer. The reduced bonding area increases the likelihood of peeling or delamination.